What is a nano quadrotor?

MIT graduate student Daniel Soltero demonstrates the use of a quadrotor inside the MIT Computer Science and Artificial Intelligence Laboratory. The nano quadrotor is a much smaller version of this.See robot pictures.

Jessica Rinaldi/For The Washington Post via Getty Images

The Rise of the Machines. It's not just the title of the dreadful third installment of the "Terminator" movie franchise; it's also a good way to describe a recent wave of advances in technology that have robots performing a wide variety of complicated tasks, from trading stocks to harvesting crops to performing surgery. With great technological ability, however, often comes even greater (and probably justified) paranoia. The idea of robots and other forms of rogue technology taking over the planet is a well-worn one in literature, television and film. Way back in 1968 Stanley Kubrick introduced us to HAL, a sensitive supercomputer that could control a high-powered spacecraft and ward off those who tried to usurp his power at the same time [source: Ebert].

These days, one of the most ominous depictions of the power of robot technology is a YouTube video of a swarm of 20 small drones humming along in unison, dipping through windows, changing formations and even zipping around in a synchronized figure-eight pattern. All without a human controlling them.

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Developed by engineers at the University of Pennsylvania's General Robotics, Automation, Sensing and Perception (GRASP) laboratory, a nano quadrotor is a tiny robot programmed to do big things in the air. These autonomous machines are equipped with four tiny propellers at each corner and designed for what their creators call "agile flight": soaring through the air in concert with one another like a flock of pelicans (or maybe a formation of droid starfighters fresh from the set of "Star Wars"). Not only can quadrotors fly in complex formations, they can also change formations seamlessly in midair -- from a four-by-five rectangle to an "x" pattern, for example -- as well as navigate various obstacles. Videos have captured the robots performing a number of other tasks, including building simple structures and performing the James Bond theme song [sources: Davies, Owano, Saenz].

So just how do these things work? Nano quadrotor developers aren't giving up all of their secrets, but there are some clues.

How a Nano Quadrotor Works

A nano quadrotor is simply a scaled down version of a quadrotor, a larger machine that uses the power of four rotors to levitate and fly. Roughly 8 inches (20 centimeters) in diameter, the nano edition weighs in at about 2 ounces (57 grams) and uses 15 watts of power. The machine hovers when all four rotors spin at the same speed and can move and change directions by varying the velocity of one or more rotor [source: Kumar].

The quadrotor's ability to pirouette through the air like a whirling dervish, dodging obstacles and navigating tight spaces, depends on both rotor speed and the rapid pace at which the robot obtains and processes information. Motion capture cameras tell the quadrotor where it is -- as well as where any obstacles may be -- 100 times per second, while an onboard processor sends commands to the motors in each propeller a whopping 600 times each second [source: Kumar].

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What is truly remarkable about the technology, however, is the nano quadrotor's capacity to monitor its surroundings and coordinate with other aerial robots to act together without crashing into one another. The machines can literally come within inches of one another while maintaining stability. That means these miniature drones can draw on combined strength to lift objects together. For example, developers used an algorithm to tell a handful of individual robots which object to pick up, when to pick it up and where to do it, an exercise that resulted in a quadrotor-created tower [source: Kumar].

Outside the friendly confines of a laboratory, a quadrotor can familiarize itself with its surroundings using the motion capture camera and a laser scanner to essentially map out nearby features -- doorways, people, furniture -- and position itself accordingly in real time. The robot then monitors its own movements with respect to the features, using a kind of personalized coordinate system [source: Kumar].

You probably don't need a physics or engineering degree to understand that nano quadrotor technology is powerful stuff. Nor do you need to be a panic-mongering conspiracy theorist to have legitimate concerns about how it may be used. While developers, law enforcement officers and politicians have touted the potential of similar drone technology to change the way we live, some observers are also worried about the implications for personal privacy [source: Kumar].

The Smarty Arts

University of Pennsylvania's GRASP lab isn't just the birthplace for the nano quadrotor. It's also a breeding ground for a broad spectrum of technological research and development. Among other notable projects, GRASP students and faculty are working on a smart wheelchair that a user can navigate with a virtual interface and onboard cameras, a personalized stroke rehabilitation system that draws on motion capture capabilities and omnidirectional video cameras [source: University of Pennsylvania].

Nano Quadrotor Uses and Concerns

There is seemingly no end to the potential uses for a nano quadrotor and the technology behind it. The first responders to a crime scene or natural disaster area, for example, may one day be tiny flying robots who relay information to the authorities a safe distance away. That's not to mention carrying out equally dangerous military operations. Meanwhile, huge swarms of quadrotors may eventually be used to perform larger scale construction projects than those already conducted at the GRASP lab [sources: Searles, Owano].

Dr. Vijay Kumar, a University of Pennsylvania professor who helped develop the technology with former students Daniel Mellinger and Alex Kushleyev, has said that the goal of this and similar projects is to determine whether "large numbers of autonomously functioning vehicles" can be "reliably deployed to carry out a prescribed mission," particularly in a potentially hostile environment and possibly with roles that change based on the circumstances [source: SWARMS]. In other words, a nano quadrotor mission could be just about anything under the sun. That type of power raises significant privacy concerns.

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Quadrotors are essentially drones, except smarter. Their autonomous swarm behavior means that these flying robots don't have to be programmed individually. Like the covert, hulking and sometimes deadly vehicles that are more frequently occupying airspace around the globe, quadrotors carry with them potential privacy abuses that have moved many American states to limit their domestic use [sources: Searles, Owano].

A law passed in February 2012 paves the way for the Federal Aviation Administration to approve unmanned aircraft for civilian use beginning in 2015. Among other proposed uses, drones are likely to be marketed for tasks as varied as monitoring crops, tracking animal migration and protecting international borders. As the drone technology increases, it's likely to become less costly. At least one developer, China's DJI, is already hocking commercially available, video-camera-ready flying drones, and another is reportedly working on a nano quadrotor with a photo camera on board [sources: Kuruvilla, Ackerman, Svensson].

The fear is that the power of cheap surveillance is one that is likely to corrupt. If nano quadrotors and other drone technology become as widely available as say, iPads, they could be used as spying devices by law enforcement agencies, paparazzi and corporations, as well as any Joe on the street who wants to keep tabs on his neighbors. That's not to mention the personal injury and property damage that an errant drone crash could cause. As a result, federal and state officials in the U.S. are creating policy standards to protect individual privacy and safety concerns while allowing users to tap the significant potential of drone technology. Just like the nano quadrotors themselves, the regulatory field in which they will eventually operate is still a work in progress [sources: Kuruvilla, Svensson].

Author's Note: What is a nano quadrotor?

After writing about the National Security Agency in one recent assignment and drafting a 20-question zombie apocalypse-themed quiz in another, I've developed a skeptic's concern for my personal privacy and a healthy fear of the brain hungry undead. So perhaps it's no surprise that a glimpse at 20 soulless drones humming in perfect formation set me a little on edge. Let's just hope nobody teaches those things how to eat ... or check my e-mail.